Recently, organic semiconductor devices represented by an organic thin-film transistor have attracted attention owing to characteristics such as saving of energy, low costs, and flexibility which inorganic semiconductor devices lack. The organic thin-film transistor is composed of several kinds of materials such as an organic semiconductor active phase, a substrate, an insulating phase, and electrodes. Of these, an organic semiconductor active phase in charge of carrier movement of charges plays a primary role in the device. The performance of the semiconductor device is affected by the carrier mobility of an organic material constituting the organic semiconductor active phase.
As processes for preparing the organic semiconductor active phase, there are generally known a vacuum deposition process which is carried out by vaporizing an organic material at a high temperature under vacuum and a coating process wherein an organic material is dissolved in a suitable solvent and the solution is applied. The coating can be also carried out using a printing technology without using high-temperature and high-vacuum conditions. Since a significant reduction of production costs of the device preparation can be achieved by printing, the coating process is a preferable process from an economical viewpoint. However, hitherto, there is a problem that it is increasingly difficult to form the semiconductor active phase from a material by the coating process as the performance of the material increases as an organic semiconductor.
For example, it has been reported that a crystalline material such as pentacene has a high carrier mobility equal to amorphous silicon and exhibits excellent semiconductor device properties (see Non-Patent Document 1). Also, there has been reported an attempt to produce the device by the coating process through dissolution of a polyacene such as pentacene (see Patent Document 1). However, since pentacene has a low solubility owing to its strong cohesiveness, high-temperature heating or the like conditions are necessary for applying the coating process. Furthermore, since a solution of pentacene is extremely easily oxidized with oxygen, the application involves difficulty from processing and economical viewpoints. Moreover, a self-assembling material such as poly(3-hexylthiophene) is soluble in a solvent and device preparation by coating has been reported. However, since the carrier mobility is one figure lower than that of a crystalline compound (see Non-Patent Document 2), there is a problem that the resulting organic semiconductor device shows a low performance.
Moreover, these organic semiconductor materials are known to show p-type semiconductor properties. For constructing an energy-saving circuit, both of p-type and n-type conductors are necessary. It is known that replacement of hydrogen of a p-type organic semiconductor material with fluorine affords a material showing n-type semiconductor properties. For example, perfluoropentacene shows n-type semiconductor properties. (see Non-Patent Document 3). However, there is a problem that a special fluorinating agent is required and also the yield in fluorination is low.
Moreover, unsubstituted terphenylene is a rigid rod-like molecule and is known to have a structure resembling pentacene but is unstable. Furthermore, a synthetic process thereof has a large number of steps and involves a step including a photoreaction, so that it is industrially not a preferable process for production (see Non-Patent Document 4).    Non-Patent Document 1: “Journal of Applied Physics”, (USA), 2002, vol. 92, pp. 5259-5263    Non-Patent Document 2: “Science”, (USA), 1998, vol. 280, pp. 1741-1744    Non-Patent Document 3: “Journal of American Chemical Society”, (USA), 2004, vol. 126, pp. 8138-8140    Non-Patent Document 4: “Journal of American Chemical Society”, (USA), 1985, vol. 107, 5670-5687    Patent Document 1: WO2003/016599 pamphlet